%0 Journal Article %A A. A. Liverovskiy %A N. N. Petrov %T Some differential-topological problems in control theory %J Differencialʹnye uravneniâ %D 1991 %P 771-777 %V 27 %N 5 %I mathdoc %U http://geodesic.mathdoc.fr/item/DE_1991_27_5_a5/ %G ru %F DE_1991_27_5_a5